CN220692814U - Ground protection circuit, controller and electric equipment - Google Patents

Abstract

The utility model relates to a grounding protection circuit, a controller and electric equipment, wherein the grounding protection circuit is provided with a voltage reduction circuit, a switch circuit and a grounding signal detection circuit, wherein the voltage reduction circuit and the switch circuit are connected in series between an alternating current live wire and a ground wire, the grounding signal detection circuit is used for detecting whether the voltage reduction circuit outputs effective voltage, and an MCU is used for controlling the switch conduction of the switch circuit in a very short time so as to realize effective grounding. The safe and effective mode realizes that the electric appliance can be effectively grounded in detection state when being electrified and started every time, and when the electric appliance is identified as not being effectively grounded, the MCU can feed back to a user and control the corresponding circuit to stop working, thereby realizing the working safety of electric equipment.

Description

Ground protection circuit, controller and electric equipment

Technical Field

The utility model relates to a ground protection circuit, a controller and electric equipment, and belongs to the field of ground protection control circuits.

Background

Some high-power electric equipment such as a water heater, a water pump, a heat pump or high-power floor type air conditioning equipment and the like have high working power consumption, the shell part of the machine type shell is exposed as a sheet metal part, the shell is required to be safely grounded for safe working, the outdoor unit and the indoor unit part of the high-power air conditioning equipment generally need to be independently connected in the installation process, and installation personnel easily cause ground wire leakage or misplacement in the connection process, so that the safety problem is caused.

Disclosure of Invention

Aiming at the existing electrical appliance controller, the technical problem to be solved by the utility model is to solve the safety problem caused by missed connection or wrong grounding wire of the whole machine.

The utility model provides a grounding protection circuit which is characterized by comprising a voltage reduction circuit, a grounding signal detection circuit, an MCU and a switch circuit; the two input ends of the voltage reducing circuit are respectively connected in series with a loop between an input alternating-current live wire and a ground wire, the grounding signal detection circuit is connected in parallel with two output ends of the voltage reducing circuit, two ends of the switch output of the switch circuit are connected in series with a loop between the alternating-current live wire and the ground wire, and the output end of the grounding signal detection circuit and the control end of the switch circuit are respectively connected with the MCU.

Optionally, the step-down circuit includes a first capacitor, a second resistor, a first diode, a second diode, a first zener diode, and a first electrolytic capacitor; one end of the first capacitor is an input end of the grounding protection circuit, the other end of the first capacitor is connected with one end of the second resistor, the other end of the second resistor is connected with an anode of the first diode and a cathode of the second diode, the anode of the first voltage-stabilizing diode and a cathode of the first electrolytic capacitor are connected with an output end cathode of the voltage-reducing circuit, and the cathode of the first diode, the cathode of the first voltage-stabilizing diode and an anode of the first electrolytic capacitor are connected with the other input end of the grounding protection circuit and the anode of the output end of the voltage-reducing circuit.

Optionally, the ground signal detection circuit includes a fourth resistor, a first optocoupler, a sixth resistor, and a seventh resistor; the positive electrode of the first optocoupler is an anode input end of the grounding signal detection circuit, the cathode of the first optocoupler is connected with one end of the fourth resistor, the other end of the fourth resistor is an anode input end of the grounding signal detection circuit, the collector of the first optocoupler is connected with the positive electrode of the first direct current power supply, the emitter of the first optocoupler is commonly connected with one end of the sixth resistor and one end of the seventh resistor, the other end of the sixth resistor is grounded, and the other end of the seventh resistor is an output end of the grounding signal detection circuit.

Optionally, the ground signal detection circuit includes a first isolation transformer, a fifth diode, and a second electrolytic capacitor; the primary input end of the first isolation transformer is an input end of the grounding signal detection circuit, the first secondary of the first isolation transformer is connected with the anode of the fifth diode, the second secondary of the first isolation transformer is commonly connected with the cathode of the second electrolytic capacitor and the ground, and the cathode of the fifth diode is commonly connected with the anode of the second electrolytic capacitor and the output end of the grounding signal detection circuit.

Optionally, the switching circuit includes a first relay and a relay driving circuit, wherein one end of a coil of the first relay is connected with the positive electrode of the second direct current power supply, the other end of the coil of the first relay is connected with the output end of the relay driving circuit, and the control end of the relay driving circuit is the control end of the switching circuit.

Optionally, the switching circuit further includes a voltage doubling control circuit, wherein two output ends of the voltage doubling control circuit are respectively connected with two ends of the coil of the first relay, and a control end of the voltage doubling control circuit is connected with an output end of the relay driving circuit.

Optionally, the relay driving circuit includes a second NPN triode and a twelfth resistor; the collector of the second NPN triode is an output end of the relay driving circuit, the emitter of the second NPN triode is grounded, the base of the second NPN triode is connected with one end of the twelfth resistor, and the other end of the twelfth resistor is a control end of the relay driving circuit.

Optionally, the voltage doubling control circuit comprises an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a fourth diode, a first PNP triode and a second electrolytic capacitor; wherein the method comprises the steps of

The cathode of the fourth diode, the anode of the second electrolytic capacitor and one end of the eleventh resistor are commonly connected to an output end of the voltage doubling control circuit, the other end of the eleventh resistor and one end of the ninth resistor are commonly connected to the other output end and the control end of the voltage doubling control circuit, the anode of the fourth diode, the emitter of the first PNP triode and one end of the eighth resistor are commonly connected to the anode of the second direct current power supply, the base of the first PNP triode, the other end of the eighth resistor, one end of the tenth resistor and the other end of the ninth resistor are commonly connected to the cathode of the second electrolytic capacitor, and the other end of the tenth resistor is grounded.

Optionally, the ground signal detection circuit further includes a third light emitting diode, an anode of the third light emitting diode is connected to one end of the second resistor, and a cathode of the third light emitting diode is connected to the other end of the first capacitor.

The utility model also provides a controller provided with the grounding protection circuit.

The utility model also provides electric equipment, which comprises the controller.

By arranging the voltage reducing circuit and the switch circuit which are connected in series between the alternating-current live wire and the ground signal detection circuit for detecting whether the voltage reducing circuit outputs effective voltage or not, when the MCU is effective in grounding, the MCU controls the switch of the switch circuit to be conducted in a very short time, the voltage reducing circuit outputs effective low voltage which is detected by the ground signal detection circuit and is output to the MCU, so that the voltage reducing circuit is identified by the MCU, and if the ground wire is not effectively grounded, the voltage reducing circuit cannot output effective voltage and is detected by the ground signal detection circuit, so that the MCU cannot identify that the system has correct and effective ground wire. Through the safe and effective mode, whether the effective electric appliance grounding state is detected is realized, and when the effective electric appliance grounding state is identified as the ineffective grounding state, the MCU can timely feed back to a user to rectify and control the corresponding circuit to stop working, so that the working safety of electric equipment is realized.

Drawings

FIG. 1 is a schematic circuit diagram of an embodiment of a ground protection circuit according to an embodiment of the present utility model;

FIG. 2 is a schematic circuit diagram of a second embodiment of the ground protection circuit of the present utility model;

FIG. 3 is a schematic circuit diagram of a third embodiment of the ground protection circuit of the present utility model;

fig. 4 is a schematic circuit diagram of a fourth embodiment of the ground protection circuit of the present utility model.

Detailed Description

In addition, in the case where the structure or the function is not conflicting, the embodiments of the present utility model and the features in the embodiments may be combined with each other. The utility model is described in detail below with reference to examples.

The utility model proposes a ground protection circuit, as shown in fig. 1, the ground protection circuit includes a step-down circuit 30, a ground signal detection circuit 20, an MCU10 and a switch circuit 40; the two input ends of the voltage reducing circuit 30 are respectively connected in series with a loop between the input ac live wire ACL and the ground wire PE, the ground signal detecting circuit 20 is connected in parallel with two output ends of the voltage reducing circuit 30, two ends of the switch output of the switch circuit 40 are connected in series with a loop between the ac live wire and the ground wire, and the output end of the ground signal detecting circuit 20 and the control end of the switch circuit 40 are respectively connected with the MCU10.

When the above ground protection circuit works, the two ends of the switch of the voltage reducing circuit 30 and the switch circuit 40 are connected in series in the loop between the ac live wire ACL and the ground wire PE, the MCU10 controls the switch of the switch circuit 40 to be closed in a short time, such as about 100ms, so that the loop is formed between the ac live wire and the ground wire, so that the voltage reducing circuit 30 outputs a low voltage, which is detected by the ground signal detecting circuit 20, and thus outputs an effective ground signal to the MCU10, which is identified by the MCU10 to be determined as effective ground of the ground wire terminal, and if the ground wire terminal is not effectively grounded, the loop cannot be formed between the live wire and the ground wire, so that the MCU10 cannot detect an effective ground signal. Since the MCU10 controls the switch to be turned on only in a very short time, the switch is generally controlled to act at the time of powering up the electric equipment applied by the ground protection circuit, so that the work of the electric equipment is not affected, and the leakage current of the equipment is not caused to cause the leakage current switch protection action of the ac line.

The grounding protection circuit of the utility model realizes the grounding effect by arranging the voltage reducing circuit 30 and the switching circuit 40 which are connected in series between the alternating-current live wire and the ground wire and the grounding signal detection circuit 20 which detects whether the voltage reducing circuit 30 has the output effective voltage or not, and the MU 10 controls the switch conduction of the switching circuit 40 in a very short time, when the voltage reducing circuit 30 outputs the effective low voltage which is detected by the grounding signal detection circuit 20 and is output to the MCU10 so as to be identified by the MCU10, and if the ground wire is not effectively grounded, the voltage reducing circuit 30 cannot output the effective voltage and is detected by the grounding signal detection circuit 20 so that the MCU10 cannot identify that the system has the correct effective ground wire. Through the safe and effective mode, whether the effective electric appliance grounding state is detected is realized, and when the effective electric appliance grounding state is identified as the ineffective grounding state, the MCU10 can timely feed back to a user to rectify and control a corresponding circuit to stop working, so that the working safety of electric equipment is realized.

Specifically, as one specific circuit of the ground protection circuit, as shown in fig. 1, the step-down circuit 30 includes a first capacitor C1, a second resistor R1, a first diode D1, a second diode D2, a first zener diode DZ1, and a first electrolytic capacitor E1; one end of the first capacitor C1 is an input end of the ground protection circuit, the other end of the first capacitor C1 is connected to one end of the second resistor R1, the other end of the second resistor R1 is commonly connected to an anode of the first diode D1 and a cathode of the second diode D2, an anode of the first zener diode DZ1 and a cathode of the first electrolytic capacitor E1 are commonly connected to an output end cathode of the voltage reduction circuit 30, and a cathode of the first diode D1, a cathode of the first zener diode DZ1 and an anode of the first electrolytic capacitor E1 are commonly connected to another input end of the ground protection circuit and an output end anode of the voltage reduction circuit 30.

Further, as shown in fig. 1, the ground signal detection circuit 20 includes a fourth resistor R4, a first optocoupler U1, a sixth resistor R6, and a seventh resistor R7; the anode of the first optocoupler U1 is an anode input end of the ground signal detection circuit 20, the cathode of the first optocoupler U1 is connected to one end of the fourth resistor R4, the other end of the fourth resistor R4 is an cathode input end of the ground signal detection circuit 20, the collector of the first optocoupler U1 is connected to the positive electrode of the first direct current source, such as +5v, the emitter of the first optocoupler U1 is commonly connected to one end of the sixth resistor R6 and one end of the seventh resistor R7, the other end of the sixth resistor R6 is grounded, and the other end of the seventh resistor R7 is an output end of the ground signal detection circuit 20.

The operation principle of the step-down circuit 30 and the ground signal detection circuit 20 is as follows: the first capacitor C1, the second resistor R1, the first diode D1, and the second diode D2 form a half-wave rectifying and voltage-reducing circuit 30, where the first capacitor C1 and the second resistor R1 are key elements for voltage reduction, and an RC voltage-reducing mode is formed. The specific capacity of the first capacitor C1 and the resistance of the second resistor R1 are determined according to the step-down value, for example, a 224pF capacitor and a 47 Ω resistor may be used, and a large-resistance first resistor R1 may be connected in parallel to the first capacitor C1 to play a role of quickly discharging the electric quantity on the capacitor when the power is off, where the resistance is generally set to about several hundred K to 1M ohms. The first diode D1 and the second diode D2 realize half-wave rectification after voltage reduction, the first voltage stabilizing diode DZ1 realizes voltage stabilization of the output voltage after voltage reduction and rectification, and the first electrolytic capacitor E1 realizes smooth filtering of the output voltage, so that stable low-voltage direct current such as 5V is formed at two ends of the first electrolytic capacitor E1. The low-voltage direct current formed from two ends of the first electrolytic capacitor E1 is reduced by the fourth resistor R4 to provide working voltage for two ends of the light emitting diode of the first optocoupler U1, and the voltage emitter of the output of the first optocoupler U1 is input to an I/O pin of the MCU10 after being limited by the seventh resistor R7 as shown as P6 in FIG. 1. The sixth resistor R6 plays a role of forcibly pulling down the ground when the output part of the first optocoupler U1 is not turned on. When the ground wire PE is effectively grounded, after the MCU10 controls the switch of the switch circuit 40 to be conducted for a short time, a passage is formed between an input live wire and the ground wire, so that the input voltage is reduced by the first capacitor C1 and the second resistor R1, and a low voltage is formed at two ends of the first electrolytic capacitor E1 after half-wave rectification by the first diode and the second diode, the low voltage enables the light emitting diode of the first optocoupler U1 to be lightened, the PN junction of the output end of the first optocoupler U1 is conducted, so that a high level is output to the MCU10, the MCU10 detects the high level, the MCU is identified as an effective ground wire of an electric appliance or an electric appliance, and if the high level is not detected, the MCU can output a corresponding prompt such as display or sound alarm mode to be fed back to a user by the controller of the electric appliance, so that the user can regulate and change in time.

Further, the step-down circuit 30 may further include a third resistor R3, where two ends of the third resistor R3 are connected in parallel to two ends of the first capacitor C1, and perform a voltage stabilizing function together with the first zener diode DZ 1.

Further, the ground signal detection circuit 20 may further include a fifth resistor R5, where the fifth resistor R5 is connected in parallel to two ends of the anode and the cathode of the first optocoupler U1, and plays a role in limiting voltage of the light emitting diode in the first optocoupler U1.

In some embodiments of the present utility model, as another implementation of the ground signal detection circuit 20, as shown in fig. 4, the circuit may include a first isolation transformer T1, a fifth diode D5, and a second electrolytic capacitor E2; the primary input end of the first isolation transformer T1 is an input end of the ground signal detection circuit 20, the first secondary of the first isolation transformer T1 is connected to the anode of the fifth diode D5, the second secondary of the first isolation transformer T1 is commonly connected to the cathode of the second electrolytic capacitor E2 and ground, and the cathode of the fifth diode D5 is commonly connected to the anode of the second electrolytic capacitor E2 and the output end of the ground signal detection circuit 20.

Unlike the optocoupler-based detection circuit of fig. 1 to 3 in the above embodiment, the circuit is based on an isolation transformer, in which the primary two ends of the first isolation transformer T1 are connected to two ends of the ac voltage output by the step-down circuit, the fifth diode is used for rectifying the voltage output by the secondary of the first isolation transformer T1 to realize output dc, and the second electrolytic capacitor E2 is used for filtering the dc. Since the secondary side of the first isolation transformer T1 is half-wave rectified by the fifth diode, the primary input of the first isolation transformer T1 is ac, and the corresponding step-down circuit can be further simplified at this time, as shown in fig. 4, where the step-down circuit removes the half-wave rectifying and filtering part circuit, that is, the first diode D1, the second diode D2, the first zener diode DZ1, the first electrolytic capacitor E1, the second resistor R2, the third resistor R3, the fourth resistor R4, and the fifth resistor R5, and only the first capacitor C1 and the first resistor R1 for RC step-down remain. At this time, the alternating current between the alternating current live wire and the ground wire at the input end of the voltage reduction circuit is reduced by RC formed by the first capacitor C1 and the first resistor R1, and then low-voltage alternating current is output to the primary two ends of the first isolation transformer T1 of the grounding signal detection circuit 20, and the corresponding alternating current is output from the secondary two ends of the first isolation transformer T1, and is subjected to half-wave rectification by the fifth diode D5 and filtering by the second electrolytic capacitor E2, so that an effective grounding detection signal is output to the MCU.

In some embodiments of the present utility model, as shown in fig. 1, the switching circuit 40 includes a first relay K1 and a relay driving circuit 41, wherein one end of a coil of the first relay K1 is connected to a positive electrode of the second dc power source as +12v in fig. 1, the other end of the coil of the first relay K1 is connected to an output terminal of the relay driving circuit 41, and a control terminal of the relay driving circuit 41 is a control terminal of the switching circuit 40. The relay driving circuit 41 can be a conventional driving circuit such as a triode-based driving circuit.

Further, in some embodiments of the present utility model, as shown in fig. 2, the switch circuit 40 further includes a voltage doubling control circuit 42, wherein two output terminals of the voltage doubling control circuit 42 are respectively connected to two ends of the coil of the first relay K1, and a control terminal of the voltage doubling control circuit 42 is connected to an output terminal of the relay driving circuit 41. The voltage doubling control circuit 42 plays a role in doubling the voltage loaded at the control end of the first relay K1, so that the first relay K1 can be quickly attracted within 10ms, and the grounding protection circuit needs to control the first relay K1 to be turned on and then turned off in a very short time, so that the normal operation of equipment is not interfered, and the safety of the operation of the circuit is improved.

Specifically, as shown in fig. 3, as a specific implementable circuit of the relay driving circuit 41 and the voltage doubler control circuit 42, the relay driving circuit 41 includes a second NPN triode Q2 and a twelfth resistor R12; the collector of the second NPN triode Q2 is an output end of the relay driving circuit 41, the emitter of the second NPN triode Q2 is grounded, the base of the second NPN triode Q2 is connected to one end of the twelfth resistor R12, and the other end of the twelfth resistor R12 is a control end of the relay driving circuit 41.

The voltage doubling control circuit 42 comprises an eighth resistor R8, a ninth resistor R9, a tenth resistor 10, an eleventh resistor R11, a fourth diode D4, a first PNP triode Q1 and a second electrolytic capacitor E2; the cathode of the fourth diode D4, the anode of the second electrolytic capacitor E2, and one end of the eleventh resistor R11 are commonly connected to an output end of the voltage doubling control circuit 42, the other end of the eleventh resistor R11 and one end of the ninth resistor R9 are commonly connected to another output end and a control end of the voltage doubling control circuit 42, the anode of the fourth diode D4, the emitter of the first PNP transistor Q1, and one end of the eighth resistor R8 are commonly connected to the anode of the second dc power supply, the base of the first PNP transistor Q1, the other end of the eighth resistor R8, one end of the tenth resistor R10, and the other end of the ninth resistor R9 are commonly connected to the cathode of the second electrolytic capacitor E2, and the other end of the tenth resistor R10 is grounded.

The operation principle of the relay driving circuit 41 and the voltage doubler control circuit 42 is as follows: when the first relay K1 is not turned on, the P4 port of the MCU10 outputs a low level, the second NPN triode Q2 is turned off, so that the first PNP triode Q1 is also turned off, the positive electrode of the second dc power supply charges the second electrolytic capacitor E2 through the fourth diode D4 as the positive electrode of +12v voltage in fig. 3, so that the two ends of the second electrolytic capacitor E2 are charged to 12V, when the P4 port of the MCU10 outputs a high level, the second NPN triode Q2 is turned on, so that the first PNP triode Q1 is also turned on, at this time, the positive electrode of the 12V voltage is instantly loaded on the negative electrode of the second electrolytic capacitor E2, so that the voltage of the positive electrode end of the second electrolytic capacitor E2 is doubled to 24V, and the voltage of 24V is loaded on the two ends of the control end of the first relay K1, so that the first relay K1 is rapidly attracted. Thus, the grounding protection circuit can complete the detection of grounding in a very short time.

Further, in some embodiments of the present utility model, as shown in fig. 1 to 3, the ground signal detection circuit 20 further includes a third light emitting diode D3, an anode of the third light emitting diode D3 is connected to one end of the second resistor R1, and a cathode of the third light emitting diode D3 is connected to the other end of the first capacitor C1. The third light emitting diode D3 is connected in series in a loop formed by the live wire ACL and the ground wire PE, when the live wire ACL and the ground wire PE are conducted and form back, the third light emitting diode D3 is lightened, namely, in the short-time working process of the grounding protection circuit, the third light emitting diode D3 is correspondingly shiny, so that indication information of good grounding is given at the same time, and whether the grounding is good or not is judged in a visual mode of relevant staff is facilitated.

The utility model also provides a controller provided with the grounding protection circuit, and the controller has a function of detecting whether the grounding is good in a very short time by arranging the grounding protection circuit.

The utility model also provides electric equipment which comprises the controller, wherein the electric equipment can be an air conditioner, heat pump equipment such as a heat pump water heater, heat pump heating equipment, a heat pump air conditioner and the like, and can also be water pump equipment running at variable frequency and the like. By adopting the controller, the electric equipment can detect whether the grounding is good or not in a very short time, remind a user to rectify and limit the operation of the equipment, and ensure the safety and reliability of the operation of the equipment.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present utility model. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present utility model, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.

While embodiments of the present utility model have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the utility model, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the utility model.

Claims (10)

1. The grounding protection circuit is characterized by comprising a voltage reduction circuit, a grounding signal detection circuit, an MCU and a switch circuit; wherein the method comprises the steps of

The two input ends of the voltage reducing circuit are respectively connected in series with a loop between an input alternating-current live wire and a ground wire, the grounding signal detection circuit is connected in parallel with the two output ends of the voltage reducing circuit, the two ends of the switch output of the switch circuit are connected in series with the loop between the alternating-current live wire and the ground wire, and the output end of the grounding signal detection circuit and the control end of the switch circuit are respectively connected with the MCU.

2. The ground protection circuit of claim 1, wherein the voltage step-down circuit comprises a first capacitor, a second resistor, a first diode, a second diode, a first zener diode, and a first electrolytic capacitor; wherein the method comprises the steps of

One end of the first capacitor is an input end of the grounding protection circuit, the other end of the first capacitor is connected with one end of the second resistor, the other end of the second resistor is commonly connected with the anode of the first diode and the cathode of the second diode, the anode of the first voltage-stabilizing diode and the cathode of the first electrolytic capacitor are commonly connected with the cathode of the output end of the voltage-reducing circuit, and the cathode of the first diode, the cathode of the first voltage-stabilizing diode and the anode of the first electrolytic capacitor are commonly connected with the other input end of the grounding protection circuit and the anode of the output end of the voltage-reducing circuit.

3. The ground protection circuit of claim 1, wherein the ground signal detection circuit comprises a fourth resistor, a first optocoupler, a sixth resistor, and a seventh resistor; wherein the method comprises the steps of

The positive electrode of the first optocoupler is the positive electrode input end of the grounding signal detection circuit, the negative electrode of the first optocoupler is connected with one end of the fourth resistor, the other end of the fourth resistor is the negative electrode input end of the grounding signal detection circuit, the collector of the first optocoupler is connected with the positive electrode of the first direct current power supply, the emitter of the first optocoupler is commonly connected with one end of the sixth resistor and one end of the seventh resistor, the other end of the sixth resistor is grounded, and the other end of the seventh resistor is the output end of the grounding signal detection circuit.

4. The ground protection circuit of claim 1, wherein the ground signal detection circuit comprises a first isolation transformer, a fifth diode, and a second electrolytic capacitor; wherein the method comprises the steps of

The primary input end of the first isolation transformer is the input end of the grounding signal detection circuit, the first secondary of the first isolation transformer is connected with the anode of the fifth diode, the second secondary of the first isolation transformer is commonly connected with the cathode of the second electrolytic capacitor and the ground, and the cathode of the fifth diode is commonly connected with the anode of the second electrolytic capacitor and the output end of the grounding signal detection circuit.

5. The ground protection circuit of claim 1, wherein the switching circuit comprises a first relay and a relay driving circuit, wherein one end of a coil of the first relay is connected with a positive electrode of a second direct current power supply, the other end of the coil of the first relay is connected with an output end of the relay driving circuit, and a control end of the relay driving circuit is a control end of the switching circuit.

6. The ground protection circuit of claim 5, wherein the switching circuit further comprises a voltage doubling control circuit, wherein two output terminals of the voltage doubling control circuit are respectively connected to two ends of the coil of the first relay, and a control terminal of the voltage doubling control circuit is connected to an output terminal of the relay driving circuit.

7. The ground protection circuit of claim 5, wherein the relay driver circuit comprises a second NPN triode and a twelfth resistor; wherein the method comprises the steps of

The collector of the second NPN triode is the output end of the relay driving circuit, the emitter of the second NPN triode is grounded, the base of the second NPN triode is connected with one end of the twelfth resistor, and the other end of the twelfth resistor is the control end of the relay driving circuit.

8. The ground protection circuit of claim 6, wherein the voltage doubler control circuit comprises an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a fourth diode, a first PNP transistor, and a second electrolytic capacitor; wherein the method comprises the steps of

The cathode of the fourth diode, the anode of the second electrolytic capacitor and one end of the eleventh resistor are commonly connected to an output end of the voltage doubling control circuit, the other end of the eleventh resistor and one end of the ninth resistor are commonly connected to another output end and a control end of the voltage doubling control circuit, the anode of the fourth diode, the emitter of the first PNP triode and one end of the eighth resistor are commonly connected to the anode of the second direct current power supply, the base of the first PNP triode, the other end of the eighth resistor, one end of the tenth resistor and the other end of the ninth resistor are commonly connected to the cathode of the second electrolytic capacitor, and the other end of the tenth resistor is grounded.

9. A controller, characterized in that the controller is provided with a ground protection circuit as claimed in any one of claims 1 to 8.

10. A powered device comprising the controller of claim 9.